1. Field of the Invention
The invention relates to a circuit board, more particularly to a printed circuit board.
2. Description of the Related Art
As shown in FIG. 1 and FIG. 2, a metal support 105 is provided in a conventional notebook computer (not shown), and is disposed between a housing (not shown) and a conventional printed circuit board 100 to enhance structural strength of the conventional notebook computer. In order to minimize electromagnetic interference and avoid creating short circuits between the metal support 105 and circuit traces on the conventional printed circuit board 100, the conventional printed circuit board 100 is configured with a routing-limited area 101 for supporting the metal support 105 thereon, in which routing in this area is prohibited. However, with the advances of notebook computers, while the size of notebook computers is to remain compact and small, the routing-limited area 101 is inevitably used for routing (i.e., having signal traces 102, test points 103 or conductive vias 104 provided thereon). In order to prevent short circuits between the metal support 105 and the signal traces 102, the test points 103 and/or the conductive vias 104, an insulating film 106 (e.g., biaxially-oriented polyethylene terephthalate (boPET), such as Mylar®) is generally provided between the metal support 105 and the conventional printed circuit board 100. However, since the metal support 105 is supported on the insulating film 106 at locations corresponding to the signal traces 102, the test points 103 and/or the conductive vias 104 at the routing-limited area 101 (only to the test point 103 in FIG. 2), whose surface areas are relatively small, the insulating film 106 tends to wear out at these locations, which may lead to short circuits.